The present invention relates, in general, to ultrasonic surgical clamping instruments and, more particularly, to a multifunctional curved shears blade for an ultrasonic surgical clamping instrument.
This application is related to the following copending patent applications: application Ser. No. 08/948,625 filed Oct. 10, 1997 now U.S. Pat. No. 6,068,647; application Ser. No. 08/949,133 filed Oct. 10, 1997 now U.S. Pat. No. 5,947,984; application Ser. No. 09/106,686 filed Jun. 29, 1998 now abandoned; application Ser. No. 09/337,077 filed Jun. 21, 1999 now U.S. Pat. No. 6,214,023; application Ser. No. 09/412,557 now abandoned; application Ser. No. 09/412,996; and application Ser. No. 09/412,257 now U.S. Pat. No. 6,325,811 which are hereby incorporated herein by reference.
Ultrasonic instruments, including both hollow core and solid core instruments, are used for the safe and effective treatment of many medical conditions. Ultrasonic instruments, and particularly solid core ultrasonic instruments, are advantageous because they may be used to cut and/or coagulate organic tissue using energy in the form of mechanical vibrations transmitted to a surgical end-effector at ultrasonic frequencies. Ultrasonic vibrations, when transmitted to organic tissue at suitable energy levels and using a suitable end-effector, may be used to cut, dissect, or cauterize tissue. Ultrasonic instruments utilizing solid core technology are particularly advantageous because of the amount of ultrasonic energy that may be transmitted from the ultrasonic transducer through the waveguide to the surgical end-effector. Such instruments are particularly suited for use in minimally invasive procedures, such as endoscopic or laparoscopic procedures, wherein the end-effector is passed through a trocar to reach the surgical site.
Ultrasonic vibration is induced in the surgical end-effector by, for example, electrically exciting a transducer which may be constructed of one or more piezoelectric or magnetostrictive elements in the instrument hand piece. Vibrations generated by the transducer section are transmitted to the surgical end-effector via an ultrasonic waveguide extending from the transducer section to the surgical end-effector.
Solid core ultrasonic surgical instruments may be divided into two types, single element end-effector devices and multiple-element end-effector. Single element end-effector devices include instruments such as scalpels, and ball coagulators, see, for example, U.S. Pat. No. 5,263,957. While such instruments as disclosed in U.S. Pat. No. 5,263,957 have been found eminently satisfactory, there are limitations with respect to their use, as well as the use of other ultrasonic surgical instruments. For example, single-element end-effector instruments have limited ability to apply blade-to-tissue pressure when the tissue is soft and loosely supported. Substantial pressure is necessary to effectively couple ultrasonic energy to the tissue. This inability to grasp the tissue results in a further inability to fully coapt tissue surfaces while applying ultrasonic energy, leading to less-than-desired hemostasis and tissue joining.
The use of multiple-element end-effectors such as clamping coagulators include a mechanism to press tissue against an ultrasonic blade, that can overcome these deficiencies. A clamp mechanism disclosed as useful in an ultrasonic surgical device has been described in U.S. Pat. Nos. 3,636,943 and 3,862,630 to Balamuth. Generally, however, the Balamuth device, as disclosed in those patents, does not coagulate and cut sufficiently fast, and lacks versatility in that it cannot be used to cut/coagulate without the clamp because access to the blade is blocked by the clamp.
Ultrasonic clamp coagulators such as, for example, those disclosed in U.S. Pat. Nos. 5,322,055 and 5,893,835 provide an improved ultrasonic surgical instrument for cutting/coagulating tissue, particularly loose and unsupported tissue, wherein the ultrasonic blade is employed in conjunction with a clamp for applying a compressive or biasing force to the tissue, whereby faster coagulation and cutting of the tissue, with less attenuation of blade motion, are achieved.
Improvements in technology of curved ultrasonic instruments such as described in U.S. patent application Ser. No. 09/106,686 previously incorporated herein by reference, have created needs for improvements in other aspects of curved clamp coagulators. For example, U.S. Pat. No. 5,873,873 describes an ultrasonic clamp coagulating instrument having an end-effector including a clamp arm comprising a tissue pad. In the configuration shown in U.S. Pat. No. 5,873,873 the clamp arm and tissue pad are straight.
The shape of an ultrasonic surgical blade or end-effector used in a clamp coagulator device defines at least four important aspects of the instrument. These are: (1) the visibility of the end-effector and its relative position in the surgical field, (2) the ability of the end-effector to access or approach targeted tissue, (3) the manner in which ultrasonic energy is coupled to tissue for cutting and coagulation, and (4) the manner in which tissue can be manipulated with the ultrasonically inactive end-effector. It would be advantageous to provide an improved ultrasonic clamp coagulator optimizing these four aspects of the instrument.
Idemoto, et al. discloses a surgical ultrasonic horn used in a surgical operation comprising a horn body and an end plate portion. Cutting portions are provided on an edge and an end of the end portion. A passage for irrigation solution extends in the horn body and the end plate portion. At least one bore opens at the cutting portions by a jet angle of 5.degree. to 90.degree. in respect of a plane of the end plate portion. The irrigation solution passage communicates with the bore, thereby the irrigation solution is sprayed therethrough.
It would be advantageous to deliver ultrasonic power more uniformly to clamped tissue than predicate devices. It would also be advantageous to provide for improved visibility of the end-effector so that a surgeon can verify that the blade extends across the structure being cut/coagulated. It would also be advantageous to provide for improved tissue access with the end-effector more closely replicating the curvature of biological structures. It would also be advantageous to provide a multitude of edges and surfaces, designed to provide a multitude of tissue effects: clamped coagulation, clamped cutting, grasping, back-cutting, dissection, spot coagulation, tip penetration and tip scoring. It would also be advantageous to provide an ultrasonic clamp coagulator that self-tensions tissue during back-cutting, utilizing a slight hook-like or wedge-like action. It would further be advantageous to provide a multifunctional ultrasonic surgical blade using unique geometric features to include: compatibility with a clamping member, sharp features for cutting, curvature for access and visibility, and a more uniform delivery of ultrasonic power than predicate devices. The present invention provides these features and improvements as described below.
Disclosed is an ultrasonic surgical instrument that combines end-effector geometry to best affect the multiple functions of a shears-type configuration. The shape of the blade is characterized by a radiused cut to form a curved and potentially tapered geometry. This cut creates a curved surface including, in one embodiment, a concave surface and a convex surface. The convex surface transitions into a short, straight, flat surface. The length of this straight portion affects, in part, the acoustic balancing of the transverse motion induced by the curved shape. Relative to straight blade tips, the tip curvature of the present design provides improved visibility of the transection site and improved access to targeted tissues. In one embodiment, an ultrasonic blade is described comprising a broad edge and a narrow edge. The broad edge opposes the narrow edge along a vertical plane, wherein the narrow edge is defined by the intersection of a first surface and a second surface, wherein the first surface is concave.